Geofoam to Reduce Roadway Load

Geofoam to Reduce Roadway Load

The natural engineering tendency when posed with a loading problem is to find a way to support it. An equally good question to ask is – can the load be reduced?

The James Road project in Weybridge, VT is an excellent example. The solution was the first known use of Geofoam as a full-scale slope stabilization repair for a roadway in Vermont.

James Road was built many years ago into an existing slope on native clay soils. In the 1970s, up to 10 feet of fill was added to change the road level. The weight of the fill over the years caused sliding and movement, followed by ongoing periodic placement of additional pavement to maintain the roadway grade. Eventually, up to six feet of pavement accumulated.

GeoDesign recommended unloading the roadway by replacing eight feet of the roadway fill with lightweight Geofoam. Geofoam is a trade name for an expanded polystyrene (EPS) material that is manufactured in large lightweight structural blocks. Geofoam weighs 2 pounds per cubic foot. Compare this to typical roadway backfill at 120 pounds per cubic foot and the Geofoam presents a sizeable reduction in load applied to the slope.

Using Geofoam blocks, the load on this slope was reduced to lower future repair and maintenance cost.

The design and construction consisted of excavating the full depth of the roadway repair followed by placement of granular bedding, drainage layers, Geofoam blocks and then finally-repaving.